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Battery recommendation...with external amp
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Okay, I looked up the power requirements for my MX-P50M 45 watt amplifier. It calls for 8A @ 13.8 volts to put out full power. Now, I have a 12V to 13.8V boost converter (designed for powering automobile accessories at full power with the engine turned off). What sort of battery should I get to power the Bitx40 and the amplifier together, for any reasonably long period of operation (like Field Day, where I would allow the battery to charge overnight while I was sleeping)? Rich KC8MWG |
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M Garza
I am not sure, either.? Maybe a motocycle battery? I am still waiting on the radio.? I have a 12v 7AH battery that I plan to use with the radio and a 1.5W solar panel to charge it.? I want to see how that holds up before I add an amp.? I plan to put about 30W or so after it, but that will probably require a bigger battery (maybe a second 7AH battery might be enough for intermittent amp use). Just my plan, that might change after I get the radio. Marco - KG5PRT On Jan 22, 2017 7:01 PM, "Richard Andrew Knack via Groups.Io" <ihc73scout2=[email protected]> wrote:
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That battery should have 12v*7AH = 84 Watt-Hours of power in it. ?Will take at least 84/1.5 = 56 hours of full sunlight perpendicular to the panel to recharge the battery. ?Assuming the rig is 6 Watts at 50% efficiency (so draws 12 Watts), could run the rig for 84/12 = 7 hours of continuous transmitting, perhaps 10 times that for just receive. ?Could deal with your 30 Watt amp as well, for a while. A starting battery like that is built for occasional high current draw for a few seconds. ?They are not built to be repeatedly discharged. ?So the lead plates are more of a lead foam, for maximum surface area, and disintegrate after the battery is discharged a few times. ?Avoid discharging below 11v or so, and always charge it back up as soon as possible to avoid sulfation. The motorcycle battery will get you started but will wear out with use. ?There are deep-cycle lead acid batteries built to be discharged 1000 times, that is not one of them. ?A lithium-ion battery pack might be a better choice long term. ? I doubt that panel will be worth the bother, though when the sun is out it should at least keep up with the Bitx40 receive current draw. All near and dear to my heart. ?We're fully off grid, running from an 18 KWh deep cycle lead acid battery bank in the basement and 4400 Watts of solar panels out in the yard. Jerry, KE7ER |
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M Garza
Jerry, WOW.? Completely off grid.? Nice. I guess I need to investigate better batteries (NI-MH maybe?) and solar/wind power.? I live near the coast, in S. Texas.? Plenty of sun and wind. ? Marco - KG5PRT On Jan 22, 2017 9:28 PM, "Jerry Gaffke via Groups.Io" <jgaffke=[email protected]> wrote:
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Jack Purdum
Marco: I don't know how "portable" you need to be, but I've used a 10W panel with my Forty-9er and it worked well. I was given a 7AH motorcycle battery, so that's what I used. I don't use it a lot, but when I have, it worked fine. As I recall, the panel is about 17"x10" and weighed about 3.5lbs. I also used a cheap ($10) solar panel charge regulator with the setup. I kept all of the electronics and battery in a toolbox. (I had an Arduino controlled stepper motor that adjusted the panel throughout the day so it always faced the sun. You can see it in the Arduino Projects for Amateur Radio book.) Jerry's suggestion for a different battery makes sense and may be cheaper in the long run. Jack, W8TEE From: M Garza <mgarza896@...> To: [email protected] Sent: Sunday, January 22, 2017 10:38 PM Subject: Re: [BITX20] Battery recommendation...with external amp Jerry,
WOW.? Completely off grid.? Nice. I guess I need to investigate better batteries (NI-MH maybe?) and solar/wind power.? I live near the coast, in S. Texas.? Plenty of sun and wind. ? Marco - KG5PRT On Jan 22, 2017 9:28 PM, "Jerry Gaffke via Groups.Io" <jgaffke=[email protected]> wrote:
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M Garza
Thanks for the info, Jack.? The battery is a sealed lead acid from a game feeder.? I had it & the solar panel, so I though I would use them.? I want to be able to hike out to the shore (3 miles or so) with everything. Since I will be playing with arduino now, I should pickup that book. Thank you everyone, for the direction and suggestions. Sorry Rich, I did not mean to hijack the thread. Marco - KG5PRT On Jan 22, 2017 11:24 PM, "Jack Purdum via Groups.Io" <econjack=[email protected]> wrote:
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If I had the motorcycle battery handy, I'd certainly use it. ?Check water levels occasionally if it has vent caps, especially if it's on the charger much. ?I even suggested somebody try a motorcycle battery here a few weeks ago when I thought they might be having trouble with their switching power supply. ?But they aren't built to give a lot of discharge cycles, and lithium is far better than lead if you are going to be lugging it around in a backpack. ?
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Sounds like I would be well off going LIPO, I don't want to go with an automotive or RV battery - I have to lug one of those when I go camping anyway, as I run a CPAP on an inverter when I am sleeping (if I start out fully charged it lasts a full weekend), but I really don't want to run my radio equipment off the same battery, for obvious reasons. If I can charge my radio battery packs off my car's battery overnight, then run the car engine for a bit to charge the car battery back up, or run a SMALL solar charger during the day to charge spare packs (big panels get expensive...), that would be fine as well. I live in northern Michigan so we don't get as much sun (or wind, most of the time) as the fellow in Texas does... Rich KC8MWG On Monday, January 23, 2017 1:12 AM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:
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An easy bet would be a pre fabricated lipo pack. ?The kind that the RC people use. ?Check out hobbyking.com. Probably a 4s pack of some kind. You could also build something out of 18650s if you are willing to solder.? Keep in mind that lithium packs have a significant voltage drop over the course of discharge. |